Endogenous Endophthalmitis by Chrysosporium: An Opportunistic Pathogen

Endogenous endophthalmitis (also known as metastatic endophthalmitis) is a rare entity that accounts for 5–7% of endophthalmitis cases.1,2 It is often seen among intravenous drug abusers and in patients with immune deficiency due to various causes.3,4 Fungal etiology is reported in 50–62% of cases, with Candida being the most common isolate, followed by Aspergillus.3 We report a rare case of bilateral metastatic endophthalmitis caused by saprophytic Chrysosporium. To our knowledge this condition has not been previously reported in literature.

Case Report

A 42-year-old man presented with complaint of sudden onset, progressive diminution of vision, associated with pain and redness in both eyes for 5 days. The patient denied any history of previous ocular disease, trauma, or intravenous drug use.

Presenting visual acuity was light perception only in right eye and finger counting close to face in left eye. Anterior segment biomicroscopy showed anterior chamber (AC) cells 4+, flare 3+, retrolental cells 4+, with pigments deposited over anterior lens capsule OU. Faint glow was appreciated on distant direct ophthalmoscopy bilaterally; indirect ophthalmoscopy showed the presence of dense vitreous exudates (OD > OS) with grade 4 media haze. Ultrasonography revealed vitreal and subretinal echoes in the posterior pole OU. He had an episode of urinary tract infection a week ago for which he was treated with oral antibiotics only. He had also been treated for pulmonary tuberculosis 6 months back and suffered from type 2 diabetes mellitus for which he was on insulin therapy for the last 5 years. General physical examination revealed pallor and bipedal pitting edema.

A provisional diagnosis of bilateral panuveitis with severe vitreal exudation was made, with the differential diagnosis of metastatic endophthalmitis. He was treated with intravenous ceftazidime (1 g 12 hourly) and vancomycin (750 mg 12 hourly) along with topical antibiotics and steroids (4 hourly) and cycloplegics (8 hourly). Hemogram and renal and liver function tests were within normal limits, VDRL was nonreactive, ELISA for HIV was negative, and blood and urine cultures were sterile. Chest x-ray showed a small area of fibrosis in the right upper lobe suggestive of a healed tuberculous lesion. CECT chest confirmed the radiographic findings with no evidence of any cavitatory lesion or enlarged lymph nodes, and hence broncho-alveolar lavage was not indicated.

In the absence of clinical improvement on medical management, pars plana vitrectomy was performed in the right eye on the fourth day of hospitalization. Intraoperatively, dense vitreous exudates resembling fungal balls and submacular exudates were noted, confirming sonographic findings and ruling out an autoimmune etiology for disease. The obtained vitreal biopsy was sent for Gram staining, KOH wet mount, and bacterial and fungal cultures. Diluted intravitreal amphotericin B (1 μg/0.1 mL) was injected intravitreally. Postoperatively, intravenous antibiotics were continued with the addition of oral itraconazole (200 mg BD) for 3 weeks. Topical antibiotics and cycloplegics were continued.

Media cleared sufficiently to allow visualization of the optic disc on the fourth postoperative day. Anterior chamber and retrolental cells, however, persisted at 4+ with light perception only OD. Pars plana vitrectomy OS was done 1 week later. Peroperative findings were similar to those of the right eye. Treatment was continued as before. Two days following surgery OS, the optic disc could be visualized bilaterally with vision of counting fingers.

FIGURE 1. (A) Lactophenol cotton blue (LCB) mount showing pyriform-shaped, thick-walled conidia (arrow) with sparse conidiophores (star). (B) Culture on Sabouroud's dextrose agar (SDA) slant shows grayish white aerial mycelia (arrow) with radial folding.

Bacterial culture of vitreous exudates thus obtained peroperatively was sterile; and fungal cultures showed growth of Chrysosporium. At 5 months follow-up, the patient had BCVA of counting fingers at 1 m in both eyes and ocular examination revealed attached retina, clear media, and disc pallor.

Discussion

Endogenous endophthalmitis is defined as intraocular infection resulting from hematogenous spread of organisms to the eye. It can occur at any age, ranging from 1 week to 85 years.5 Bilateral involvement is seen in 14–25% of patients with no sex preponderance.5,6 Often, patients have predisposing conditions like diabetes mellitus, urinary tract infection, endocarditis, meningitis, pneumonia, gastrointestinal malignancy, history of invasive procedures like intravenous infusions, and drug abuse. Among these, diabetes mellitus is the most common risk factor, with prevalence ranging from 60 to 90% in patients with endogenous endophthalmitis.7,8 This is due to neutrophilic dysfunction, which weakens the host defense barrier.

Chrysosporium is a keratinophilic filamentous fungus commonly isolated from soil where it lives on remains of hairs and feathers.9,10 Ubiquitous in nature, it is a common cause of pulmonary disease in burrowing rodents. In humans, the only reported disease associated with Chrysosporium is adiaspyromycosis. The latter is a form of pulmonary mycosis characterized by intrapulmonary growth of inhaled conidia of Chrysosporium fungus, which incite granulomatous response sometimes with the development of large, thick-walled, spherule-like structures called adiaspores. Naturally occurring adiaspiromycosis is restricted to the lungs, as inhaled conidia do not replicate or disseminate, although, rarely, they can result in human disease involving other organ systems. At least 5 cases with Chrysosporium as the causative agent have been described in humans where different organs were affected, and bone was involved in 3 of them.10–14 Among ocular infections, Chrysosporium has been reported to cause keratomycosis, with subsequent perforation in a healthy male.15 However, a Medline search did not reveal any cases of intraocular infection with Chrysosporium.

Since our patient was a farmer living in the countryside with a past history of tuberculosis, there is a possibility that fungal spores colonized his healed tuberculous lesion and metastasized hematogenously in the state of relative immunosuppression secondary to diabetes. Pulmonary colonization of Chrysosporium secondary to prior tuberculosis has also been reported in the past.

Among all antifungals, Chrysosporium shows sensitivity to amphotericin B only in vivo and additionally to itraconazole in vitro. Since our patient was not found to have any systemic focus of fungal infection and amphotericin B has significant systemic toxicity, we treated our patient with oral itraconazole postoperatively after the microbiological report was confirmed. To conclude, bilateral metastatic endophthalmitis due to Chrysosporium is a rare clinical entity that has not been reported in the past and has poor visual outcome. Early vitrectomy along with systemic antifungal cover should be provided to control the disease.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.